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Thread: Layman's question on mutations

  1. #1 Layman's question on mutations 
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    First I would like to say that I am not a natural scientist so my knowledge about this is pretty limited. In that vein, if you notice that my understanding of some concepts is flawed I would appreciate if you would point it out. Also, english is not my first language so please excuse my grammar.


    I have been wondering, what does it mean that mutations are random? To be more precise, what does the term „random“ denote. Does it mean that:



    1) Mutations are not directed towards organisms' fitness.

    2) Mutations are truly random in the sense like decay of unstable atoms is random – no matter how controlled the enviorement is, it is only possible to give a probabilistic solution when and which mutations will occur.

    3) Mutations are called random because we do not have all the needed data to predict when and which mutations will happen. Similar to flippling a coin – we can say that it is random but in principle we could calculate which side will land if we had access to all the needed data.



    From what I understand, (1) is pretty much established as true. The question I wanted to ask is if the term „random“ means only (1) or does it also have some implications in regard to (2) or (3)?


    Appreciate all input, including „you missed something obvious/this question is completley misguided"


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    Brassica oleracea Strange's Avatar
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    Interesting question. I certainly don't have the answers.

    1) Is definitely true. (With some possible caveats...)

    3) I don't think this is true of coin flipping, never mind more complex systems. It requires a level of determinism and predictability that the universe doesn't seem to have.


    2) Is the most interesting, though.

    There are many different types of mutation possible; for instance deleting or duplicating a section of DNA, transposing sequences, replacing one base with another, etc. I would guess that all these types are not equally likely. I would further assume that within each types there are some changes or locations that are more likely than others.

    And then, if the mutation is caused by some environmental factor (radiation, chemicals, etc) then these are, presumably, more likely to cause certain types of changes.

    Hopefully, someone who knows what they are talking about will be along soon ...


    ei incumbit probatio qui dicit, non qui negat
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  4. #3  
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    Thank you for the response. Though I cant help but wonder about:

    Quote Originally Posted by Strange View Post

    3) I don't think this is true of coin flipping, never mind more complex systems. It requires a level of determinism and predictability that the universe doesn't seem to have.
    If I remember correctly, somebody even made a "coin-flipper" machine that tossed the coin exactly the same to disprove what you just said. The point was that the "randomness" actually arises from our inability to toss the coin in the same way more than once. I will try and dig up the link. Though im not 100% on this.
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    Brassica oleracea Strange's Avatar
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    Quote Originally Posted by Mrav View Post
    If I remember correctly, somebody even made a "coin-flipper" machine that tossed the coin exactly the same to disprove what you just said. The point was that the "randomness" actually arises from our inability to toss the coin in the same way more than once. I will try and dig up the link. Though im not 100% on this.
    At the risk of getting off topic ... That is a bit different. I can imagine that a machine (or someone who practices a lot) could flip a coin so it always comes up the same way. Just as good stage magicians can do a perfect shuffle. But that is not quite the same thing as predicting which way a coin will land when flipped by your average Joe.

    Now something as simple as a coin flip might, just about, be predictable. But something like a quincunx (love that word) or Pachinko machine is unpredictable even in principle.
    ei incumbit probatio qui dicit, non qui negat
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    Its been a while since I taken statistics but I generally get your point about the quincunx (you are right, it is a nice word). Can't add anything though. And yes, we are going a bit off topic
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  7. #6  
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    Quote Originally Posted by Mrav View Post
    2) Mutations are truly random in the sense like decay of unstable atoms is random – no matter how controlled the enviorement is, it is only possible to give a probabilistic solution when and which mutations will occur.
    Some mutations can be caused by the radiation from the decay of unstable atoms, so I think that at least those mutations are exactly like that.
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  8. #7  
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    Mutations absolutely are not directed in any way. Certainly not toward increasing an organism's fitness. They are changes in the genotype. Period. Not positive changes, just changes.

    It is certainly possible to increase the rate of mutation with various kinds of insults to the organism, exposure to various types of radiation, chemicals, viruses etc. Certain types of viral insult might carry the possiblity of inducing a particular mutation rather than just a random one. This is because viral insult actually brings foreign genetic material into a cell.

    Even mutation based on damage to the genetic material from radiation might not be entirely random in its results on the next generation because of resistence that the particular organism to genetic damage. Living things have redundancies built into them. We have two lungs, two kidneys etc. Cells also can have redundant pathways for the production of specific proteins. Redundant systems enhance survivablity and so are selected for.
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